The present invention relates generally to moisture analyzers. More specifically, the present invention relates to a continuous flow moisture analyzer for determining the moisture content in a sample material under test.
Various manufacturing processes, chemical reactions, and laws attendant certain industries require that the percentage of certain volatile fluids of interest present within a product be known. Indeed, the determination of moisture (or volatile) content in materials is of such importance in so many fields that a wide variety of devices and analytical methods have been developed to provide such information. One such analytical moisture analysis method is a chemical analysis method known as the Karl Fischer technique. The Karl Fischer moisture analysis technique is a method of titrating a test sample with a reagent to determine trace amounts of water in the test sample. Unfortunately, chemical analysis methods rely on the use of various reagents which may be toxic. Moreover, such chemical analysis methods usually require very skilled operators and are often quite time consuming.
Moisture analysis devices include, for example, vacuum ovens and convection ovens which heat a test sample of the product to a temperature commensurate with the volatile fluid of interest to cause evaporation of such fluid. Devices of this type are often referred to as loss on drying analyzers. Using a loss on drying moisture analyzer, the resulting reduction in weight of the test sample provides data for computing the percent by weight of the volatile fluid of interest in the test sample. Various computational techniques may be employed to forecast the percentage determination based upon the initial weight loss rate. Such computational approximations reduce the time required to complete a test without serious derogation of the accuracy of the determination. Loss on drying techniques are limited to approximately 0.1% minimum moisture loss due to secondary effects such as convective air currents, buoyancy effects, and temperature gradients. In addition, loss on drying techniques can sustain some degree of measurement error relative to the accuracy of the scale used for weighing the test sample.
Other moisture analysis devices employ sensors that measure the quantity of volatile fluid in a gas stream to determine the amount of volatile fluid in a test sample. For example, one such moisture analyzer includes a test sample heater, a dry carrier gas flow system, and a moisture transducer. The moisture analyzer heats a sample of test material contained in a septum bottle. The dry gas is injected into the septum bottle and absorbs the moisture out of the sample material. The dry gas, carrying the moisture from the sample, is ejected from the septum bottle and transported to the moisture transducer where the moisture content of the flowing gas is measured. A processor then integrates the varying moisture signal and converts the integrated signal to total moisture content. Using the sample weight and the total moisture content value, the moisture concentration in the test sample is subsequently calculated.
Unfortunately, problems such as pre-existing moisture levels, transient response times, and contamination render the measurement of moisture content inaccurate. In one such moisture analyzer, uncontrolled moisture can be introduced into the dry carrier gas flow system. This uncontrolled moisture results in a non-consistent baseline, which consequently leads to inaccuracy in the measurement of the moisture content in the sample material.
Accordingly, it is an advantage of the present invention that a continuous flow moisture analyzer is provided.
It is another advantage of the present invention the continuous flow moisture analyzer efficiently and accurately determines the moisture content in a sample of dry material.
It is another advantage of the present invention that the continuous flow moisture analyzer accurately determines the moisture content in a sample material by substantially preventing the introduction of uncontrolled moisture in the gas flow system of the moisture analyzer.
The above and other advantages of the present invention are carried out in one form by a continuous flow moisture analyzer including a first needle portion having a first channel for receiving a carrier gas and having an output orifice from the first channel for expelling the carrier gas and a second needle portion having an input orifice for receiving the carrier gas expelled from the output orifice and having a second channel in communication with the input orifice for transporting the carrier gas. A housing encloses the output orifice and the input orifice when the moisture analyzer is in a standby mode. A bottle retains a sample material when the moisture analyzer is in an active mode. The bottle has a septum configured to face the housing, the first and second needle portions penetrating the septum to position the output and input orifices in the bottle. The carrier gas expelled from the output orifice absorbs moisture from the sample material, and a moisture sensor in fluid communication with the second channel detects moisture in the carrier gas.
The above and other advantages of the present invention are carried out in another form by a continuous flow moisture analyzer. The continuous flow moisture analyzer includes a coaxial needle having a first end and a second end. The coaxial needle includes a first needle portion having a first channel for receiving a carrier gas and having an output orifice from the first channel for expelling the carrier gas. The coaxial needle further includes a second needle portion having an input orifice for receiving the carrier gas expelled from the output orifice and having a second channel in communication with the input orifice for transporting the carrier gas. The output orifice and the input orifice are located proximate the second end. A housing encloses the output orifice and the input orifice when the moisture analyzer is in a standby mode. The housing includes a track in non-moving relation with the coaxial needle, and a sleeve slidably coupled to the track. A bottle retains a sample material and is configured to abut the sleeve when the moisture analyzer is in an active mode. The bottle has a septum facing the sleeve. When the bottle abuts the sleeve, the sleeve retracts along the track to allow the coaxial needle to penetrate the septum to position the output and input orifices in the bottle. The carrier gas expelled from the output orifice absorbs moisture from the sample material, and a moisture sensor in fluid communication with the second channel detects the moisture in the carrier gas.
The above and other advantages of the present invention are carried out in yet another form by a continuous flow moisture analyzer. A continuous flow moisture analyzer a first needle portion having a first channel for receiving a carrier gas and having an output orifice from the first channel for expelling the carrier gas and a second needle portion having an input orifice for receiving the carrier gas expelled from the output orifice and having a second channel in communication with the input orifice for transporting the carrier gas. A housing encloses the output orifice and the input orifice when the moisture analyzer is in a standby mode. The housing includes a track in non-moving relation with the coaxial needle, and a sleeve slidably coupled to the track. A bottle retains a sample material when the moisture analyzer is in an active mode. The bottle has a septum configured to face the housing. The moisture analyzer further includes a transport mechanism for conveying the bottle toward the housing so that the first and second needle portions penetrate a center portion of the septum to position the output and input orifices in the bottle. The carrier gas expelled from the output orifice absorbs moisture from the sample material, and a moisture sensor in fluid communication with the second channel detects the moisture in the carrier gas.